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The present invention relates to a device for use in combination with pile driving apparatus for driving piles into and out of the ground, the device including a vibratory force generating means.
In order to drive piles into the ground, it is known to apply rapid hammer blows to the pile by means of a vibratory force generator. In such known systems, a steady force is applied to the pile by, typically, hydraulic means and the vibratory force generator is disposed between the point of application of the steady force and the pile. It is also known from, for example EP 648297, to apply the vibratory force through apparatus which grips the pile. For driving long piles and in situations where it is not possible to obtain free access above the pile, it is known to grip the pile intermediate its length by sideways extending gripper arms and to transmit the vibratory force through the gripper arms. As shown in EP 648297 it is also known for the gripper arms to be pivotable between the horizontal position for gripping a pile intermediate its length and a vertical position for gripping the end of a pile for the completion, or start, of pile driving or removal.
The known systems have the disadvantage that the vibratory forces are transmitted through pivot pins, by which the gripper arms are pivoted between their various positions, and piston rods of the gripper means. Because of their nature, these points constitute weak areas in the passage of the driving force which limits the amount of driving force which can be applied to the pile and also results in a short life for the components.
It is also known from JP58117129 to provide a device for driving piles which is suitable for connection to a force generating machine. An oil-pressure vibro device transmits a vibratory force directly to a vertical chuck or a horizontal chuck. However, the range of movement of the gripping means is very limited. It is not possible to manipulate the gripping means to pick up a pile from the ground and place the pile in a upright position for driving.
The present invention seeks to provide improved means for transmitting the driving forces to the pile.
According to the present invention there is provided a device for use in combination with a force generating apparatus for driving piles into and out of the ground, the device including a main body having a vibratory force generator and first gripping means which, when the main body is in the operative orientation to enable vertical pile driving to take place, extends horizontally from the main body for gripping a vertically disposed pile intermediate its length, and second gripping means extending from the main body generally perpendicularly downwardly relative to the first gripping means for gripping the end of a vertically disposed pile, characterized in that resilient means are interposed between the main body and coupling means through which coupling means the device is adapted to be connected to the force generating apparatus, the coupling means being drivably pivotable in more than one plane.
In an alternative aspect of the present invention there is provided a device for use in combination with a force generating apparatus for driving piles into and out of the ground, the device including a main body, resilient means interposed between the main body and coupling means through which coupling means the device is adapted to be connected to the force generating apparatus, the main body having a vibratory force generator and first gripping means which, when the main body is in the operative orientation to enable vertical pile driving to take place, extends generally horizontally from the main body for gripping a vertically disposed pile intermediate its length, the gripping means comprising at least one pair of horizontally opposed gripping members at least one of which is a fluid operable ram having a piston fixedly secured relative to the main body and a cylinder movable towards and away from the opposed gripping member.
When constructed according to this aspect of the invention, the device may also incorporated a said second gripping means. The second gripping means may comprise at least one pair of opposed fluid operably rams, having a piston fixedly secured to the main body and a cylinder movable by said fluid towards and away from the opposed ram.
In an alternative embodiment, the or each gripping means may comprise a fixed reaction point and a ram movable towards and away from the fixed reaction point.
In an alternative embodiment, where the gripping means comprises a pair of opposed rams, one of the rams is movable to a fixed predetermined gripping location, before the second ram completes its movement to grip a pile between the two rams.
Preferably, the or each cylinder is slidable in an associated bore in said main body.
A preferred embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: